Overflow release means.



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CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

OVERFLOW RELEASE MEANS.

Application filed April 27, 1916.

To all whom it may concern:

Be it known that 1, CHARLES L. GOODRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Overflow Release Means, of which the following is a full, clear, concise, and exact description.

This invention relates to circuit arrangements for overflow release of line finder and selector switches.

One feature of this invention is the provision of means whereby the last line of a group, if it is not a selectable line, may be used to release the finder switch whenever this switch goes to that position.

Another feature of this invention resides in the use of the last trunk contact for giving a busy signal when all the trunks of a group are busy.

The drawing diagrammatically represents a portion of a telephone system employing the present invention.

The mechanism indicated within the dotted line in the drawing is individual to a subscribers line, and represents a line switch of the general character disclosed in Patent No. 1,151.543, of August 24, 1915, to A. E. Keith, Telephone exchange trunking system. To the right of the dotted rectangle, there is diagrammatically indicated a first selector switch, such as disclosed in applicants application, Serial No. 41,587, filed July 23, 1915, Automatic telephone exchange system, and circuits therefor having the present invention embodied therein.

The side switch indicated in the drawing may be similar in structure to that shown in Patent No. 815,176, March 13, 1906, Keith and Erickson. Automatic telephone connector switch, but differs therefrom in that in certain instances the wipers are moved upon the energization, instead of upon the deenergization, of the controlling magnet. A side switch of this character is disclosed in the application of O. F. Forsberg, Serial No. 6302, filed February 5, 1915, Telephone exchange switching mechanism.

It is believed that the invention will now be clearly understood by tracing the operation of setting up a connection through the selector switch shown in the drawing.

Assuming that the subscriber, whose substation apparatus is indicated at the left inthe drawing, removes his receiver from the Specification of Letters Patent.

Patented Nov. 13, 1917.

Serial No. 93,870.

hook, a circuit will be completed from battery through the left-hand winding of line relay 1, left-hand armature and back contact of cut-off relay 2, over the upper side of the line and through the substation apparatus, back over the lower side of the line, through the right-hand armature and back contact of cut-oil relay 2, and through the right-hand winding of relay 1, back to bat.- tery. Relay 1 pulls up, and completes a circuit from grounded battery, through the right-hand winding of the plunger operating magnet 3, front contact and armature of relay 1 to ground. This magnet is energized and causes the operation of the plunger or contact operating device 4, by means of which the line spring terminals 19 and 20 are forced into engagement with the trunk terminals adjacent thereto.

In accordance with the well-known operation of a switch of this character, it will be understood that the plunger at the time of its operation was associated with a contact set in which an idle trunk terminated. Upon the closure of the line and trunk contacts, a circuit is completed from grounded battery through the left-hand winding of the plunger operating magnet 3, cut-otf relay 2, the lower line switch spring 20, relay 5, and back contact and armature of release magnet 6 to ground. Magnet 3 is maintained energized and relays 2 and 5 attract their armatures. Relay 5 at its inner armature grounds the trunk contact at the master switch, thus causing the idle plungers to move to a position before the next idle trunk, in a manner clearly explained in Patent No. 1151,5 13 August 2%, 1915. to A. E. Keith, Telephone exchange trunking systems.

Simultaneously with the above. a circuit is completed from grounded battery through stepping relay 7, side-switch wiper 17, upper spring 19 and trunk terminal of the line switch, front contact and left-hand armature of relay :2, over the subscribers line and through the substation circuits, back over the other side of the line, right-hand armature and front contact of relay 2, lower line switch spring 20 and relay 5 to ground. This interrupts the circuit for the release magnet 6, which would otherwise be established from grounded battery. relay 6, outermost left-hand armature and front contact of relay 5, side-switch wiper 16, back contact and left-hand armature of slow release relay 8, back contacts and armatures of relays 7 and 9 to ground. The energization of relay 7 completes a circuit fr m grounded battery through slow-release relay 8. front contact and armature of relay 7, back contact and armature of test relay 9 to ground.

The subscriber now works his sending device to interrupt the circuit of relay 7. lVith the first det nergization of relay 7, the rotary stepping magnet 10 and the slowrelease relay 11 are energized in parallel by a circuit from battery through said relay and magnet with its controlling side-switch wiper in first position, in parallel, front contact, left-hand armature of relay 8, back contact of relay 7 and back contact and armature of relay 9. The energization of slow-release relay 11, completes a circuit for escape magnet 12, which may be traced from grounded battery, magnet 12, front contact and armature of relay 11 to ground. Helays S and 11 being slow to release, remain energized throughout the series of impulses. Each interruption of the line circuit and consequent deenergization of stepping relay 7 causes the rotary magnet 10 to move the switch brushes over the group of trunks. Upon the termination of the impulses, relay 7 remains energized, thus holding open the circuit of relay 11, which falls off and opens the previously established circuit for the escape magnet 12, thus causing the sideswitch wipers to move to their second position. In the present invention, as w'll be described later, escape magnet 12 partakes of the functions of the test relay. rlagnet 12 may therefore be regarded as a secondary test relay. In position 2 of the side switch, a circuit is established from batte y through the vertical stepping magnet 13, the individual interrupter of said magnet, sideswitch wiper 23, front contact and armature of relay 7, and back contact and armature of test relay 9 to ground. The terminals of busy trunks traversed by the lower switch brush will be provided with raised potential so that the test relay 9 will not be energized. i-Vhen, however, the switch brush engages the terminal of an idle trunk, which will be connected to earth, relay 9 will pull up, interrupting the circuit for the stepping magnet 13 and completing a circuit from grounded battery through escape magnet 12, front contact and righthand armature of slow-release relay 8, and front contact and armature of relay 9 to ground.

In the device herein disclosed, a circuit is provided for the overflow release of the selector switch whenever all ofthe trunks of the group are busy. This release means is equally effective for the release of any finder switch which has reached the last line of the group, if that line is not selectable.

T he overflow release circuit of the selector switch may be traced from grounded battery, relay 6, oft-normal contact 15, back contact and armature of magnet 12, and grounded overflow contact 18, rhich 1s closed when the switch brush engages the last line of a group of busy lines.

As previously mentioned, the escape magnet 12 partalres of the functions of a test relay. ll hen the test relay 9 is energized through a circuit completed by the switch brush engaging a grounded terminal, an energizing circuit will be completed for escape magnet This circuit may be traced from grounded battery, magnet 12, front contact, right-hand armature of relay 8, front contact and armature of relay 9 to ground. lVhen magnet 12 is energized it attracts its armature, thereby interrupting the circuit of the overflow releasing means. It should be noted that the magnet 12 is more active than magnet 6. By reason of this provision, when the switch brush has seized the last idle trunk for use, magnet 12 prevents the overflow release means from acting, since magnet 12, by the attraction of its armature, interrupts the operating circuit for that releasing means. However, when the switch brush has encountered busy trunks in the group, magnet 12 will not be energized, and its armaturewill remain in retracted position. In this case, when the switch brush engages the last line of the group, the overflow contact 18 will be closed and the release mechanism actuated. It will readily be understood that the circuit here in described as the overflow release circuit may be utilized in the transmission of busy signals, instead of effecting the release of the various automatic switches.

If the overflow release means has not been, actuated, the escape magnet is energized. and moves the side-switch wipers to position 3 in a manner which is clearly disclosed in a licants application, Serial No. 872,743, filed November 18, 1914 Automatic telephone exchange system.

As the operation of the switches succeeding the first selector may be of substantially tie same character as that shown in applicants application, Serial No. 35,326, filed June 21, 1915, Two-wire multiple automatic telephone system, the operation of establishing the rest of the connection will not be described.

Before the side switch motes to its third position, any de'energization of stepping relay 7 is momentary only and, therefore, re lay 8 remains energized. This breaks the circuit-frombattery through release magnet L sh e 6, off-normal contact 15, and side-switch wiper 16, which would otherwise be com: pleted through the back contact and armature of relay 8,back contactand armature of pulses were being sent, stepping relay 7 would fall oil, causing the deenergization of relay 8 and the completion of the release circuit just described.

At the time the side switch moves out of position 2 and the stepping relay 7 becomes deenergized, relay 9 is energized (see Goodrum Serial No. 99,756, filed May 25, 1916, automatic telephone exchange systems, page 7, lines 1-8 inclusive), but when the side switch reaches its third position, relay 9 becomes de'e'nergized, due to certain changes at the succeeding selector switch, thus opening up the release circuit which would otherwise be established from grounded battery through magnet 6, contact 15, wiper 16, back contact of relay 8, and front contact and armature of relay 9 to ground. At the termination of the conversation, relay 9 becomes energized, due to circuit changes at the succeeding switch, in a manner which will be understood from the above mentioned application, Serial No. 35,326.

Should the subscriber, after the operation of his line switch, replace his receiver on the hook without operating his sending de vice, the stepping relay 7 will become deenergized, and a circuit will be completed from grounded battery through the release magnet, the outermost left-hand armature and contact of relay 5 and wiper 16 to ground, through the back contacts and armatures of relays 8, 7 and 9 as before.

The operation of magnet 6 interrupts the circuit of relays 5 and 2 and magnet 3, and if the switch has moved from normal, magnet 6 establishes a holding circuit for itself,

which is maintained through the off-normal. contact until the switch reaches normal position.

The de'e'nergization of magnet 3 allows the plunger to be retracted. The retraction of the armatures of relay 2, connects the subscribers line to his line relay 1, and the retraction of the armatures of relay 5 removes the busy potential from the trunk contact at the master controller, thus permitting the trunk to again be selected.

T Vhat is claimed is:

1. In a telephone system, a series of lines, a switch for interconnecting said lines, testing means for said lines at said switch, release means for said switch, a circuit including said release means, means for closing a break point in said circuit when the switch contacts with the last of the series of lines, and means controlled by said testing means for positively opening another break point in said circuit when the switch engages the last line of the series, if that line is idle.

2. In a telephone system. a series of lines having fixed contacts, a switch having mov' able contacts for engagement with said fixed contacts, testing means for said lines at said switch, releasing means for said switch, a

circuit including the releasing means, two break points in said circuit, means for closing one of said break points when said movable switch contacts engage with the contacts of the last of the series of lines, and means controlled by said testing means for positively opening the other break point when the switch engages the last line of the series, if that line is idle.

3. In a telephone system, a series of lines, testing means for said lines, a switch for interconnecting said lines, releasing means for said switch, a circuit including a grounded contact and the releasing means, said circuit being grounded through said contact when the switch engages with the last line of the series, and means controlled by said testing means for opening said circuit if the last line is idle.

at. In a telephone system, a series of lines, a switch for interconnecting said lines, testing means for said lines at said switch, releasing means for said switch, a circuit including the release means and contacts, one of said contacts being normally open and another of said contacts being normally closed, means for closing said normally open contact whenever the switch engages the last line of the series, and means controlled by said testing means for opening said normally closed contact if the line engaged is idle.

5. In a telephone system, lines, a series of fixed and movable contacts in which said lines terminate, automatic means for causing said movable contacts to engage said fixed contacts. test means for said lines, release means for said movable contacts, a contact actuated upon engagement of a movable contact with the last fixed contact of the series, and a circuit for actuating said release means, said circuit being controlled at one point by the last mentioned contact and at another point by the said test means.

6. In a. telephone system, a plurality of lines, a series of fixed and movable contacts in which said lines terminate, means for causing said movable contacts to engage said fixed contacts, releasing means for said movable contacts, an overflow contact adapted to be closed by the engagement of one of said movable contacts with the last fixed contact of the series, a circuit for controlling the releasing means including the overflow contact, and means for closing said circuit under predetermined conditions by engagement of a movable contact with the last fixed contact.

7. In a telephone system, groups of incoming and outgoing lines, an automatic switch having movable contacts in which said incoming lines terminate and fixed contacts in which said outgoing lines terminate, means for causing the movable contacts to engage the fixed contacts, an oven flow contact adapted to be closed simultaneousiy with the engagement of a movable contact with the last fixed contact of the magnet, and a contact arranged to close said group, an escape magnet, an armature concircuit immediately upon the engagement rolled by said magnet, and a circuit includof the switch with the last line of the series ing the overflow contact and the armature if that line is lousy. of said escape magnet. In witness whereofi, I hereunto subscribe S. In a telephone system, a series of lines, my name this 26th day of April A. D., 1916. a switch fer interconnectingv said lines, CHARLES L. GOODRUM.

means for operating said switch, a release 10 magnet for said swltch, a clrcult for sald Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D; C. 

